1. Field of the Invention
The present invention generally pertains to an universal serial bus (USB) device, and more particularly to an USB device that accesses another USB device without going through a host computer.
2. Description of the Related Art
A portable electronic device is generally equipped with a small memory device such as a flash memory card. For instance, a digital camera (DC) or a personal digital assistant (PDA) commonly uses a flash memory card to store application data. For a small size and a big storage capacity, the flash memory card is used popularly nowadays. It is noted that an electronic device or a computer equipped with a built-in card connector can directly access a flash memory card via the built-in card connector, and if an electronic device or a computer not equipped with a built-in card connector, an external flash memory card reader is required for the electronic device or the computer to access a flash memory card. Further, in a current market, a portable data storage device that integrates a flash memory card and a flash memory card reader together into one is usually named traveling disc. Currently, a size of a traveling disc is small enough to put in a packet and not get noticed, and a storage capacity of a traveling disc is at a range of tens of mega bytes to hundreds of mega bytes. For a feature of small size, big storage capacity, and reusability, a traveling disc is getting popular to become a commonly used portable storage device and has a tendency to replace a floppy disc or a rewritable CD-ROM (compact disc—read only memory).
Upon an exploiting of a current IC technology, a newly developed traveling disc equips with a bigger storage capacity than before and uses a most popular universal serial bus (USB) as its input/output (I/O) interface, the traveling disc becomes one of the best selling computer peripheral devices in the market. However, the traveling disc is a passive device; it must depend on a host computer to store or retrieve data. Without a host computer, a traveling disc will not be able to copy or store data to another traveling disc. Further, a USB port electronic device such as a digital camera must use a computer to transfer image data to a traveling disc using a USB interface. A traveling disc can not connect to an electronic device directly to retrieve or store data.